1. Field of Invention
This invention relates to a tab-like board terminal which is designed to be inserted into a through hole in a printed circuit board to be connected thereto, and the invention also relates to a method of producing this board terminal.
2. Related Art
FIGS. 5 and 6 show a conventional method of producing board terminals. The board terminals are produced using a wide sheet 1 (shown in FIG. 5(a)) having a predetermined small thickness, for example, of 0.64 mm. Electrically-conductive metal is plated on the surfaces of the sheet 1, and then this sheet is blanked or stamped by a pressing die, thereby forming a pressed product 2 shown in FIG. 5(b).
The pressed product 2 includes two pre-shaped portions 3 (to serve as board terminals) interconnected by a first carrier portion 4 and a second carrier portion 5. The first carrier portion 4 serves as a portion through which the sheet is fed when the blanking operation is to be effected by the pressing die. The second carrier portion 5 serves to prevent the board terminals from being deformed when taking up the board terminals. These carrier portions are cut off and discarded simultaneously when cutting off the pre-shaped portions 3 from the pressed product 2.
Each of the pre-shaped portions 3 includes a tapering insertion portion 6 connected to the first carrier portion 4, a soldering portion 7 extending from the insertion portion 6, and a connection portion 8 extending from the soldering portion 7. The insertion portion 6 is adapted to be inserted into a through hole in a printed circuit board, and the soldering portion 7 is adapted to be soldered to the printed circuit board, and the connection portion 8 is adapted to be connected to a mating terminal. The blanking is effected in such a manner that the width h1 (see FIG. 6) of the soldering portion 7 is 0.60 mm, and the width h2 of the connection portion 8 is 1.00 mm.
In the above conventional method, however, a waste portion 9 as indicated by hatching in FIG. 6 is produced, and besides the first carrier portion 4 and the second carrier portion 5 must be discarded. Therefore, the loss of the material is large, and the yield rate of the products relative to the used material is low.
And besides, the plating is not formed on those portions press-cut by the pressing die, and therefore there is encountered another problem that the reliability of soldering is low. Furthermore, the pressed product 2 (shown in FIG. 5(b)) of a complicated shape is formed from the sheet 1 (shown in FIG. 5(a)), and therefore the pressing die is complicated, and is expensive.
It is therefore an object of this invention to provide a board terminal which can be formed with a reduced loss of a material, and can enhance a soldering reliability, and does not need a complicated pressing die in the production, and an another object is to provide a method of producing this board terminal.
The above object has been achieved by a board terminal of the present invention including a tapering insertion portion for insertion into a through hole in a board, a soldering portion to be soldered to the board, and a connection portion for connection to a mating terminal, the insertion portion, the soldering portion and the connection portion being continuously arranged in this order in a direction of a length of the board terminal, provided in that the insertion portion is formed by pressing a wire having a width larger than a thickness thereof, and the soldering portion is formed by cutting or pressing widthwise opposite side portions of the wire, and has a width smaller than the width of the wire.
In the board terminal of this invention, the insertion portion is formed by pressing the wire having the width larger than the thickness thereof, and the soldering portion is formed by cutting the widthwise opposite side portions of the wire, and has the width smaller than the width of the wire. Those portions, which are cut off from the wire, and are discarded, are produced only when the soldering portion is formed by the above cutting operation. Therefore, generally the whole of the wire can be formed into the board terminal, and the production can be performed with a minimum loss of the material.
The soldering portion, formed by cutting or pressing the wire, has the width which is smaller than the width of the wire, and is generally equal to the thickness of the wire, so that this soldering portion has a generally square cross-section. Therefore, a thermal stress, developing when soldering the board terminal to the printed circuit board, is uniform, and a crack will not develop during the soldering operation. And besides, since the soldering portion has a reduced width, the diameter of the through hole can be reduced, and the board terminals can be mounted at a high density on the printed circuit board.
In the first aspect of the present invention, recesses are formed in the connection portion.
The connection portion is connected to the mating terminal, and therefore part of the connection portion is embedded in the connector. In this invention, the recesses are formed in the connection portion, and a resin of the connector intrudes into the recesses, so that the resin and the recesses engage each other. Therefore, the board terminal can be stably mounted on the connector.
In the first or second aspect of the present invention, electrically-conductive metal is plated on an outer surface of the board terminal.
In this invention, since the electrically-conductive metal is plated on the outer surface, the reliability of the soldering is enhanced.
According to the present invention, there is provided a method of producing a board terminal including a tapering insertion portion for insertion into a through hole in a board a soldering portion to be soldered to the board, and a connection portion for connection to a mating terminal, the insertion portion, the soldering portion and the connection portion being continuously arranged in this order in a direction of a length of the board terminal; provided by the steps of forming the insertion portion by pressing a wire having a width larger than a thickness thereof; and forming the soldering portion by cutting or pressing widthwise opposite side portions of that portion of the wire extending fro the insertion portion, the soldering portion, the soldering portion having a width smaller than the width of the wire.
In this invention, there is used the wire having the width larger than its thickness, and the insertion portion is formed by pressing the wire, and the soldering portion is formed by cutting or pressing the widthwise opposite side portions of the wire. Therefore, there is no need to use a complicated pressing die, and the board terminal can be easily produced.
Those portions, which are cut off from the wire, and are discarded, are only those portions cut for forming the soldering portion, and therefore generally the whole of the wire can be formed into the board terminal, and therefore the production can be performed with a minimum loss of the material.
In the present invention, recesses are formed in a connection portion-forming portion of the wire simultaneously when forming the insertion portion by pressing.
In this invention, the recesses in the connection portion are formed simultaneously when forming the insertion portion by pressing, and therefore the number of the process steps is not increased, and the board terminal can be easily produced.
In the present invention, electrically-conductive metal is plated on the board terminal after the pressing or the cutting of the widthwise opposite side portions.
Only the board terminal is formed using the wire as the material, and therefore the construction is simple. Therefore, the plating can be applied to the board terminal over the entire surface thereof, and this plating enhances the reliability of the soldering.